ordered crystal. Apart from many biomedical applications, X-rays are majorly used
in the elucidation of three-dimensional structures of molecule(s) from the days
where X-rays were produced from gas tubes invented by Coolidge to the synchrotron(s) where monochromatic waves are produced and used for diffraction
whose energy may vary depending upon the source. The wavelength of X-rays
ranges from 0.8 to 2.3 Å, suitable for protein crystallography. The low wavelength
and high-energy X-rays help in analyzing the atomic details of proteins and viruses
which largely help in the structure-based drug designing. The prerequisite of this
diffraction experiment is growth of good quality single crystals. Materials in nature
(atom, molecules) possess the property to form crystalline solid, where the basic
constituents of the material tend to arrange themselves in a highly ordered manner.
This arrangement is called “crystalline lattice,” and the solid material is crystal.
Crystals are very regular in shape and highly ordered and symmetrical in nature,
which can be understood from the external examination. The periodic arrangement
of atom and ions in three-dimensional space is “crystal lattice.” The smallest
repetitive unit in three dimensions, which on translation gives the entire crystal
structure, is called “unit cell.” Depending upon the number of atoms in the molecule
which is crystallized, there are two categories, namely small molecular crystallography and macromolecular crystallography.
The structure determination of molecules which are in the range of several
hundred Daltons is named as small molecular crystallography. These structures
usually contain inorganic, organic, metallo-organic, and material structures.
Cambridge Structural Database, CSD, is the world’s repository for small molecular
organic and organo-metallic crystal structures. The CCDC plays a major role in the
collection of nearly 9, 50,000 updated entries by 2018, and this information is made
available to all scientists across the world.
The importance of enzymes, their characterization, and crystallization was stated
by Sumner, Northrup, Kunitz, Herriott and their colleagues [19–21]. These investigations proved to be an important tool in identification of the properties and nature
of catalytic mechanism of macromolecules and their nature to form crystals. There
too, many factors control the crystal growth of macromolecules. The structures of
macromolecules are deposited in Protein Data Bank (PDB) which is an open-source
database. The structure and also other experimental and relevant information are
incorporated for comparative studies. The total number of entries in PDB as of
August 2018 is 1,43,392.
Importance of protein crystallography in medicine
The availability of structural information of small molecules assisted scientists to
exploit and alter the molecule for biomedical benefits, which was evident to
crystallographers and also further in extending this method for proteins as well,
since such application has greater potential with greater degree of medical implications. The idea of structure–function relationship met with greater effect with
examples such as function of oxygen binding and affinity toward hemoglobin,
insulin function. There is a greater report on the function of proteases from different
viruses, especially, protease from HIV, where structures of apo as well as ligand
274
D. Velmurugan et al.
in the elucidation of three-dimensional structures of molecule(s) from the days
where X-rays were produced from gas tubes invented by Coolidge to the synchrotron(s) where monochromatic waves are produced and used for diffraction
whose energy may vary depending upon the source. The wavelength of X-rays
ranges from 0.8 to 2.3 Å, suitable for protein crystallography. The low wavelength
and high-energy X-rays help in analyzing the atomic details of proteins and viruses
which largely help in the structure-based drug designing. The prerequisite of this
diffraction experiment is growth of good quality single crystals. Materials in nature
(atom, molecules) possess the property to form crystalline solid, where the basic
constituents of the material tend to arrange themselves in a highly ordered manner.
This arrangement is called “crystalline lattice,” and the solid material is crystal.
Crystals are very regular in shape and highly ordered and symmetrical in nature,
which can be understood from the external examination. The periodic arrangement
of atom and ions in three-dimensional space is “crystal lattice.” The smallest
repetitive unit in three dimensions, which on translation gives the entire crystal
structure, is called “unit cell.” Depending upon the number of atoms in the molecule
which is crystallized, there are two categories, namely small molecular crystallography and macromolecular crystallography.
The structure determination of molecules which are in the range of several
hundred Daltons is named as small molecular crystallography. These structures
usually contain inorganic, organic, metallo-organic, and material structures.
Cambridge Structural Database, CSD, is the world’s repository for small molecular
organic and organo-metallic crystal structures. The CCDC plays a major role in the
collection of nearly 9, 50,000 updated entries by 2018, and this information is made
available to all scientists across the world.
The importance of enzymes, their characterization, and crystallization was stated
by Sumner, Northrup, Kunitz, Herriott and their colleagues [19–21]. These investigations proved to be an important tool in identification of the properties and nature
of catalytic mechanism of macromolecules and their nature to form crystals. There
too, many factors control the crystal growth of macromolecules. The structures of
macromolecules are deposited in Protein Data Bank (PDB) which is an open-source
database. The structure and also other experimental and relevant information are
incorporated for comparative studies. The total number of entries in PDB as of
August 2018 is 1,43,392.
Importance of protein crystallography in medicine
The availability of structural information of small molecules assisted scientists to
exploit and alter the molecule for biomedical benefits, which was evident to
crystallographers and also further in extending this method for proteins as well,
since such application has greater potential with greater degree of medical implications. The idea of structure–function relationship met with greater effect with
examples such as function of oxygen binding and affinity toward hemoglobin,
insulin function. There is a greater report on the function of proteases from different
viruses, especially, protease from HIV, where structures of apo as well as ligand
274
D. Velmurugan et al.